Summary
Objective
To demonstrate the safety and effectiveness of responsive stimulation at the seizure focus as an adjunctive therapy to reduce the frequency of seizures in adults with medically ...intractable partial onset seizures arising from one or two seizure foci.
Methods
Randomized multicenter double‐blinded controlled trial of responsive focal cortical stimulation (RNS System). Subjects with medically intractable partial onset seizures from one or two foci were implanted, and 1 month postimplant were randomized 1:1 to active or sham stimulation. After the fifth postimplant month, all subjects received responsive stimulation in an open label period (OLP) to complete 2 years of postimplant follow‐up.
Results
All 191 subjects were randomized. The percent change in seizures at the end of the blinded period was −37.9% in the active and −17.3% in the sham stimulation group (p = 0.012, Generalized Estimating Equations). The median percent reduction in seizures in the OLP was 44% at 1 year and 53% at 2 years, which represents a progressive and significant improvement with time (p < 0.0001). The serious adverse event rate was not different between subjects receiving active and sham stimulation. Adverse events were consistent with the known risks of an implanted medical device, seizures, and of other epilepsy treatments. There were no adverse effects on neuropsychological function or mood.
Significance
Responsive stimulation to the seizure focus reduced the frequency of partial‐onset seizures acutely, showed improving seizure reduction over time, was well tolerated, and was acceptably safe. The RNS System provides an additional treatment option for patients with medically intractable partial‐onset seizures.
The Neuromodulation Appropriateness Consensus Committee (NACC) of the International Neuromodulation Society (INS) evaluated evidence regarding the safety and efficacy of neurostimulation to treat ...chronic pain, chronic critical limb ischemia, and refractory angina and recommended appropriate clinical applications.
The NACC used literature reviews, expert opinion, clinical experience, and individual research. Authors consulted the Practice Parameters for the Use of Spinal Cord Stimulation in the Treatment of Neuropathic Pain (2006), systematic reviews (1984 to 2013), and prospective and randomized controlled trials (2005 to 2013) identified through PubMed, EMBASE, and Google Scholar.
Neurostimulation is relatively safe because of its minimally invasive and reversible characteristics. Comparison with medical management is difficult, as patients considered for neurostimulation have failed conservative management. Unlike alternative therapies, neurostimulation is not associated with medication-related side effects and has enduring effect. Device-related complications are not uncommon; however, the incidence is becoming less frequent as technology progresses and surgical skills improve. Randomized controlled studies support the efficacy of spinal cord stimulation in treating failed back surgery syndrome and complex regional pain syndrome. Similar studies of neurostimulation for peripheral neuropathic pain, postamputation pain, postherpetic neuralgia, and other causes of nerve injury are needed. International guidelines recommend spinal cord stimulation to treat refractory angina; other indications, such as congestive heart failure, are being investigated.
Appropriate neurostimulation is safe and effective in some chronic pain conditions. Technological refinements and clinical evidence will continue to expand its use. The NACC seeks to facilitate the efficacy and safety of neurostimulation.
Sacral neuromodulation (SNM) (sacral nerve stimulation SNS) has become an established therapy for functional disorders of the pelvic organs. Despite its overall success, the therapy fails in a ...proportion of patients. This may be partially due to inadequate electrode placement with suboptimal coupling of the electrode and nerve. Based on these assumptions the technique of sacral spinal neuromodulation has been redefined. All descriptions relate to the only currently available system licensed for all pelvic indications (Medtronic Interstim
).
An international multidisciplinary working party of ten individuals highly experienced in performing SNM convened two meetings (including live operating) to standardize the implant procedure. This report addresses the main steps to optimal electrode lead placement in temporal sequence.
Key elements of the electrode placement are radiological marking, the use of a curved stylet, the entry of the electrode into the sacral foramen and its progression through the foramen, its placement guided by a combination of a typical appearance in fluoroscopy and achieving specific motor/sensory responses with stimulation. The report describes quadripolar electrode placement and then either insertion of a connecting percutaneous extension lead or permanent implantation of the programmable device.
Standardization of electrode placement may ensure close electrode proximity to the target nerve providing a higher likelihood for optimal effect with less energy consumption (better battery longevity), more programming options with more electrode contacts close to the nerve and reduced likelihood of side-effects. The potentially better clinical outcome needs to be demonstrated.
Recent initiatives in bioelectronic modulation of the nervous system by the NIH (SPARC), DARPA (ElectRx, SUBNETS) and the GlaxoSmithKline Bioelectronic Medicines effort are ushering in a new era of ...therapeutic electrical stimulation. These novel therapies are prompting a re-evaluation of established electrical thresholds for stimulation-induced tissue damage.
In this review, we explore what is known and unknown in published literature regarding tissue damage from electrical stimulation.
For macroelectrodes, the potential for tissue damage is often assessed by comparing the intensity of stimulation, characterized by the charge density and charge per phase of a stimulus pulse, with a damage threshold identified through histological evidence from in vivo experiments as described by the Shannon equation. While the Shannon equation has proved useful in assessing the likely occurrence of tissue damage, the analysis is limited by the experimental parameters of the original studies. Tissue damage is influenced by factors not explicitly incorporated into the Shannon equation, including pulse frequency, duty cycle, current density, and electrode size. Microelectrodes in particular do not follow the charge per phase and charge density co-dependence reflected in the Shannon equation. The relevance of these factors to tissue damage is framed in the context of available reports from modeling and in vivo studies.
It is apparent that emerging applications, especially with microelectrodes, will require clinical charge densities that exceed traditional damage thresholds. Experimental data show that stimulation at higher charge densities can be achieved without causing tissue damage, suggesting that safety parameters for microelectrodes might be distinct from those defined for macroelectrodes. However, these increased charge densities may need to be justified by bench, non-clinical or clinical testing to provide evidence of device safety.
Deep-brain stimulation is the surgical procedure of choice for patients with advanced Parkinson's disease. The globus pallidus interna and the subthalamic nucleus are accepted targets for this ...procedure. We compared 24-month outcomes for patients who had undergone bilateral stimulation of the globus pallidus interna (pallidal stimulation) or subthalamic nucleus (subthalamic stimulation).
At seven Veterans Affairs and six university hospitals, we randomly assigned 299 patients with idiopathic Parkinson's disease to undergo either pallidal stimulation (152 patients) or subthalamic stimulation (147 patients). The primary outcome was the change in motor function, as blindly assessed on the Unified Parkinson's Disease Rating Scale, part III (UPDRS-III), while patients were receiving stimulation but not receiving antiparkinsonian medication. Secondary outcomes included self-reported function, quality of life, neurocognitive function, and adverse events.
Mean changes in the primary outcome did not differ significantly between the two study groups (P=0.50). There was also no significant difference in self-reported function. Patients undergoing subthalamic stimulation required a lower dose of dopaminergic agents than did those undergoing pallidal stimulation (P=0.02). One component of processing speed (visuomotor) declined more after subthalamic stimulation than after pallidal stimulation (P=0.03). The level of depression worsened after subthalamic stimulation and improved after pallidal stimulation (P=0.02). Serious adverse events occurred in 51% of patients undergoing pallidal stimulation and in 56% of those undergoing subthalamic stimulation, with no significant between-group differences at 24 months.
Patients with Parkinson's disease had similar improvement in motor function after either pallidal or subthalamic stimulation. Nonmotor factors may reasonably be included in the selection of surgical target for deep-brain stimulation. (ClinicalTrials.gov numbers, NCT00056563 and NCT01076452.)
Rapid advancements in neurostimulation technologies are providing relief to an unprecedented number of patients affected by debilitating neurologic and psychiatric disorders. Neurostimulation ...therapies include invasive and noninvasive approaches that involve the application of electrical stimulation to drive neural function within a circuit. This review focuses on established invasive electrical stimulation systems used clinically to induce therapeutic neuromodulation of dysfunctional neural circuitry. These implantable neurostimulation systems target specific deep subcortical, cortical, spinal, cranial, and peripheral nerve structures to modulate neuronal activity, providing therapeutic effects for a myriad of neuropsychiatric disorders. Recent advances in neurotechnologies and neuroimaging, along with an increased understanding of neurocircuitry, are factors contributing to the rapid rise in the use of neurostimulation therapies to treat an increasingly wide range of neurologic and psychiatric disorders. Electrical stimulation technologies are evolving after remaining fairly stagnant for the past 30 years, moving toward potential closed-loop therapeutic control systems with the ability to deliver stimulation with higher spatial resolution to provide continuous customized neuromodulation for optimal clinical outcomes. Even so, there is still much to be learned about disease pathogenesis of these neurodegenerative and psychiatric disorders and the latent mechanisms of neurostimulation that provide therapeutic relief. This review provides an overview of the increasingly common stimulation systems, their clinical indications, and enabling technologies.
Several treatment options are available for stress urinary incontinence (SUI), including pelvic floor muscle training (PFMT), drug therapy and surgery. Problems exist such as adherence to PFMT ...regimens, side effects linked to drug therapy and the risks associated with surgery. We have evaluated an alternative treatment, electrical stimulation (ES) with non-implanted devices, which aims to improve pelvic floor muscle function to reduce involuntary urine loss.
To assess the effects of electrical stimulation with non-implanted devices, alone or in combination with other treatment, for managing stress urinary incontinence or stress-predominant mixed urinary incontinence in women. Among the outcomes examined were costs and cost-effectiveness.
We searched the Cochrane Incontinence Specialised Register, which contains trials identified from the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, MEDLINE In-Process, MEDLINE Epub Ahead of Print, CINAHL, ClinicalTrials.gov, WHO ICTRP and handsearches of journals and conference proceedings (searched 27 February 2017). We also searched the reference lists of relevant articles and undertook separate searches to identify studies examining economic data.
We included randomised or quasi-randomised controlled trials of ES with non-implanted devices compared with any other treatment for SUI in women. Eligible trials included adult women with SUI or stress-predominant mixed urinary incontinence (MUI). We excluded studies of women with urgency-predominant MUI, urgency urinary incontinence only, or incontinence associated with a neurologic condition. We would have included economic evaluations had they been conducted alongside eligible trials.
Two review authors independently screened search results, extracted data from eligible trials and assessed risk of bias, using the Cochrane 'Risk of bias' tool. We would have performed economic evaluations using the approach recommended by Cochrane Economic Methods.
We identified 56 eligible trials (3781 randomised participants). Eighteen trials did not report the primary outcomes of subjective cure, improvement of SUI or incontinence-specific quality of life (QoL). The risk of bias was generally unclear, as most trials provided little detail when reporting their methods. We assessed 25% of the included trials as being at high risk of bias for a variety of reasons, including industry funding and baseline differences between groups. We did not identify any economic evaluations.For subjective cure of SUI, we found moderate-quality evidence that ES is probably better than no active treatment (risk ratio (RR) 2.31, 95% CI 1.06 to 5.02). We found a similar result for cure or improvement of SUI (RR 1.73, 95% CI 1.41 to 2.11), but the quality of evidence was lower. We are very uncertain if there is a difference between ES and sham treatment in terms of subjective cure because of the very low quality of evidence (RR 2.21, 95% CI 0.38 to 12.73). For subjective cure or improvement, ES may be better than sham treatment (RR 2.03, 95% CI 1.02 to 4.07). The effect estimate was 660/1000 women cured/improved with ES compared to 382/1000 with no active treatment (95% CI 538 to 805 women); and for sham treatment, 402/1000 women cured/improved with ES compared to 198/1000 with sham treatment (95% CI 202 to 805 women).Low-quality evidence suggests that there may be no difference in cure or improvement for ES versus PFMT (RR 0.85, 95% CI 0.70 to 1.03), PFMT plus ES versus PFMT alone (RR 1.10, 95% CI 0.95 to 1.28) or ES versus vaginal cones (RR 1.09, 95% CI 0.97 to 1.21).Electrical stimulation probably improves incontinence-specific QoL compared to no treatment (moderate quality evidence) but there may be little or no difference between electrical stimulation and PFMT (low quality evidence). It is uncertain whether adding electrical stimulation to PFMT makes any difference in terms of quality of life, compared with PFMT alone (very low quality evidence). There may be little or no difference between electrical stimulation and vaginal cones in improving incontinence-specific QoL (low quality evidence). The impact of electrical stimulation on subjective cure/improvement and incontinence-specific QoL, compared with vaginal cones, PFMT plus vaginal cones, or drugs therapy, is uncertain (very low quality evidence).In terms of subjective cure/improvement and incontinence-specific QoL, the available evidence comparing ES versus drug therapy or PFMT plus vaginal cones was very low quality and inconclusive. Similarly, comparisons of different types of ES to each other and of ES plus surgery to surgery are also inconclusive in terms of subjective cure/improvement and incontinence-specific QoL (very low-quality evidence).Adverse effects were rare: in total nine of the women treated with ES in the trials reported an adverse effect. We identified insufficient evidence to compare the risk of adverse effects in women treated with ES compared to any other treatment. We were unable to identify any economic data.
The current evidence base indicated that electrical stimulation is probably more effective than no active or sham treatment, but it is not possible to say whether ES is similar to PFMT or other active treatments in effectiveness or not. Overall, the quality of the evidence was too low to provide reliable results. Without sufficiently powered trials measuring clinically important outcomes, such as subjective assessment of urinary incontinence, we cannot draw robust conclusions about the overall effectiveness or cost-effectiveness of electrical stimulation for stress urinary incontinence in women.
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